/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2008, by Object Refinery Limited and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * ----------------
 * KeyedValues.java
 * ----------------
 * (C) Copyright 2002-2008, by Object Refinery Limited.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * Changes:
 * --------
 * 23-Oct-2002 : Version 1 (DG);
 * 12-Jan-2005 : Updated Javadocs to specify new behaviour when key
 *               is not recognised (DG);
 * ------------- JFREECHART 1.0.0 ---------------------------------------------
 * 02-May-2006 : Updated API docs (DG);
 *
 */

package net.droidsolutions.droidcharts.core.data;

import java.util.List;

/**
 * An ordered list of (key, value) items where the keys are unique and non-
 * <code>null</code>.
 * 
 * @see Values
 * @see DefaultKeyedValues
 */
public interface KeyedValues extends Values {

	/**
	 * Returns the key associated with the item at a given position. Note that
	 * some implementations allow re-ordering of the data items, so the result
	 * may be transient.
	 * 
	 * @param index
	 *            the item index (in the range <code>0</code> to
	 *            <code>getItemCount() - 1</code>).
	 * 
	 * @return The key (never <code>null</code>).
	 * 
	 * @throws IndexOutOfBoundsException
	 *             if <code>index</code> is not in the specified range.
	 */
	public Comparable getKey(int index);

	/**
	 * Returns the index for a given key.
	 * 
	 * @param key
	 *            the key (<code>null</code> not permitted).
	 * 
	 * @return The index, or <code>-1</code> if the key is unrecognised.
	 * 
	 * @throws IllegalArgumentException
	 *             if <code>key</code> is <code>null</code>.
	 */
	public int getIndex(Comparable key);

	/**
	 * Returns the keys for the values in the collection. Note that you can
	 * access the values in this collection by key or by index. For this reason,
	 * the key order is important - this method should return the keys in order.
	 * The returned list may be unmodifiable.
	 * 
	 * @return The keys (never <code>null</code>).
	 */
	public List getKeys();

	/**
	 * Returns the value for a given key.
	 * 
	 * @param key
	 *            the key.
	 * 
	 * @return The value (possibly <code>null</code>).
	 * 
	 * @throws UnknownKeyException
	 *             if the key is not recognised.
	 */
	public Number getValue(Comparable key);

}
